When we launched our Android banking app, it had one account, one portfolio and one currency. The architecture was simple because the assumptions were simple. Then the business grew. This is the story of how we evolved the business and the app into a multi-account, multi-portfolio, multi-currency platform - complete with junior accounts, four portfolio types, and two currencies - without starting from scratch. Told as a two-perspective narrative: one speaker covers the business drivers behind each evolution (why we needed it, what the market demanded), while the other covers the technical reality of making it happen on Android (what broke, what scaled, and what we'd do differently). Leave with an understanding of: - How to evolve a "single-everything" Android architecture into a multi-tenant model incrementally - Where single-account assumptions tend to hide in your codebase and how to find them before they break - Why complexity is multiplicative, not additive, when you layer multi-account, multi-portfolio, and multi-currency together Practical patterns for managing growing state and navigation complexity on Android - How tight collaboration between product and engineering makes incremental evolution possible without rewrites